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conf: Rework virDomainObjListFindByUUID to allow more concurrent APIs

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Currently, when there is an API that's blocking with locked domain and
second API that's waiting in virDomainObjListFindByUUID() for the domain
lock (with the domain list locked) no other API can be executed on any
domain on the whole hypervisor because all would wait for the domain
list to be locked.  This patch adds new optional approach to this in
which the domain is only ref'd (reference counter is incremented)
instead of being locked and is locked *after* the list itself is
unlocked.  We might consider only ref'ing the domain in the future and
leaving locking on particular APIs, but that's no tonight's fairy tale.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
This commit is contained in:
Martin Kletzander 2014-12-02 08:33:33 +01:00
parent d2632d60aa
commit feb1a4d792
3 changed files with 29 additions and 3 deletions
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29
src/conf/domain_conf.c
View File

@ -1074,8 +1074,10 @@ virDomainObjPtr virDomainObjListFindByID(virDomainObjListPtr doms,
}
virDomainObjPtr virDomainObjListFindByUUID(virDomainObjListPtr doms,
const unsigned char *uuid)
static virDomainObjPtr
virDomainObjListFindByUUIDInternal(virDomainObjListPtr doms,
const unsigned char *uuid,
bool ref)
{
char uuidstr[VIR_UUID_STRING_BUFLEN];
virDomainObjPtr obj;
@ -1084,17 +1086,38 @@ virDomainObjPtr virDomainObjListFindByUUID(virDomainObjListPtr doms,
virUUIDFormat(uuid, uuidstr);
obj = virHashLookup(doms->objs, uuidstr);
if (ref) {
virObjectRef(obj);
virObjectUnlock(doms);
}
if (obj) {
virObjectLock(obj);
if (obj->removing) {
if (ref)
virObjectUnref(obj);
virObjectUnlock(obj);
obj = NULL;
}
}
virObjectUnlock(doms);
if (!ref)
virObjectUnlock(doms);
return obj;
}
virDomainObjPtr
virDomainObjListFindByUUID(virDomainObjListPtr doms,
const unsigned char *uuid)
{
return virDomainObjListFindByUUIDInternal(doms, uuid, false);
}
virDomainObjPtr
virDomainObjListFindByUUIDRef(virDomainObjListPtr doms,
const unsigned char *uuid)
{
return virDomainObjListFindByUUIDInternal(doms, uuid, true);
}
static int virDomainObjListSearchName(const void *payload,
const void *name ATTRIBUTE_UNUSED,
const void *data)

2
src/conf/domain_conf.h
View File

@ -2287,6 +2287,8 @@ virDomainObjPtr virDomainObjListFindByID(virDomainObjListPtr doms,
int id);
virDomainObjPtr virDomainObjListFindByUUID(virDomainObjListPtr doms,
const unsigned char *uuid);
virDomainObjPtr virDomainObjListFindByUUIDRef(virDomainObjListPtr doms,
const unsigned char *uuid);
virDomainObjPtr virDomainObjListFindByName(virDomainObjListPtr doms,
const char *name);

1
src/libvirt_private.syms
View File

@ -353,6 +353,7 @@ virDomainObjListExport;
virDomainObjListFindByID;
virDomainObjListFindByName;
virDomainObjListFindByUUID;
virDomainObjListFindByUUIDRef;
virDomainObjListForEach;
virDomainObjListGetActiveIDs;
virDomainObjListGetInactiveNames;